One of the major developments in electronics recently has been the explosion in the popularity of microcontrollers, in particular the PIC series of processors. A microcontroller is effectively a simple computer on a single chip, complete with microprocessor, input/output ports, RAM and ROM to contain the program. A single 18 or 28 pin PIC processor can often replace a dozen or more conventional logic. Also, the versatility of a microprocessor based design means that it is often possible to incorporate useful extras in the design that would be difficult for impossible using conventional logic circuitry. This is an introduction to PIC microcontrollers, Topics covered in the book include: the PIC register set; numbering systems; bitwise operations and rotation; the PIC instruction set; using interrupts; suing the analogue to digital converter; clock circuits; using the real time clock counter (RTCC); subroutines; driving seven segment displays.